Industrial conveyor belts

ABSTRACT

This invention relates to bonds, and processes for making same, which are useful in the manufacture, joining, and repair of industrial conveyor belts, and endless cloth used in paper manufacturing machinery, and, more particularly, to a structurally integrated, yet pervious, laminated structure comprising a first layer intermediate and continuously bonded to second and third layers. The resultant porous laminate manufactured in accordance with the teachings of the present invention may be used in various applications related to industrial conveyor belts or papermakers clothing. For example, it may be employed to form a seam for or a patch in papermakers fabrics useful in the forming section of the typical fourdrinier papermaking machine.

United States Patent Price [451 May 23, 1972 [72] Inventor:

[52] US. Cl ..161/89, 156/298, 156/304, 161/60, 161/93, 161/96, 161/118,161/143, 161/170, 161/185 [51] Int. Cl. ..B32b 3/06, B32b 3/10, B32b27/38 [58] FieldofSearch ..16l/60,98,93,96,86, 143, 161/145, 147, 149,170, 185, 118, DIG. 4, 89; 156/298, 304, 278

[56] References Cited UNITED STATES PATENTS 3,226,275 12/1965 Kiess..161/89 X 3,581,698 6/1971 Bete ..161/185 X 3,597,300 8/1971 Miller161/86 X 3,607,599 9/1971 McPherson 161/144 3,616,112 10/1971 Desail6l/89X 3,617,613 11/1971 Benzinger 161/98 X 3,619,314 11/1971Ecureux.... ..161/145X 3,391,050 7/1968 Nebesar ..161/60 X 3,567,5683/1971 Windecker ..161/93 3,573,150 3/1971 Broutman et a1. ..161/603,393,117 7/1968 Zolg et al ..161/93 X 3,544,421 12/1970 Griffith.........l61/60 X 3,186,866 6/1965 Claeys ..161/93 X 3,400,038 9/1968Burgess.... ..161/86 X 3,441,465 4/1969 Pearson 161/86 X 3,515,6236/1970 Bates ..161/86 3,526,565 9/1970 Walter ..161/86 X PrimaryExaminer-Harold Ansher Attorney-William G. Rhines ABSTRACT Thisinvention relates to bonds, and processes for making same, which areuseful in the manufacture, joining, and repair of industrial conveyorbelts, and endless cloth used in paper manufacturing machinery, and,more particularly, to a structurally integrated, yet pervious, laminatedstructure comprising a first layer intermediate and continuously bondedto second and third layers. The resultant porous laminate manufacturedin accordance with the teachings of the present invention may be used invarious applications related to industrial conveyor belts or papermakersclothing. For example, it may be employed to form a seam for or a patchin papermakers fabrics useful in the forming section of the typicalfourdrinier papermaking machine.

14 Claims, 7 Drawing Figures Patented May 23, 1972 3,664,907

2 Sheets-Sheet l Patented May 23, 1972 2 Sheets-Sheet z INVENTOR. w BYINDUSTRIAL CONVEYOR BELTS BACKGROUND OF THE lNVENTlQN Paper machineforming media conventionally have been woven wire structures made frommaterials such as phosphor bronze, bronze, stainless steel, brass orsuitable combinations thereof. Such forming wires are woven flat inplain, twill, satin, or other suitable weave patterns. Subsequent to theweaving of the wire, the ends are joined to form an endless belt-likestructure, as by brazing the abutting ends of constituent machinedirection wires together. Recently fabrics of superior suitability foruse as forming media have been woven entirely or in part from syntheticmaterials. Nylon, a polyamide fiber, has been found to be suitable, ashave polyesters, such as Dacron, acrylic fibers such as Orlon, Dynel andAcrilan, and co-polymers such as Saran. The warp and weft yarns may beof the same or different constituent materials and/or constructions andmay be in the form of monofilament or multifilament yarns, or they maybe yarns made up of suitable strands or plies which in turn may beformed from staple fiber. Such fabrics may be woven endless, as, forexample, the fabric described and claimed in U.S. Pat. No. 2,903,021,Holden et al. However, since, in the endless woven papermakers fabricsthe filling or weft yarns extend in the machine direction when thefabric is positioned on the paper-making machine, the width of loomsused to produce a forming fabric which has been woven endless must be atleast as great as the length of the forming section of the papermakingmachine which the fabric is to clothe. Alternatively, such fabrics maybe woven flat and made endless by joining the two ends of the fabrictogether. Such a process, which usually involves handweaving, istime-consuming and expensive. Attempts have been made to join syntheticforming media using those techniques used to join both ends of formingwires. However, when, for example, synthetic monofilament yarns arewelded" together, the welds" are not as strong as the constituent yarnswhich comprise the remaining portion of the fabric, and the weld"therefore may not be strong enough to withstand the rigors to which thefabric is subjected during the papermaking operation where the formingfabric may be subjected to machine direction tensions as high as about45 pounds per lineal inch of width. The design of a seam suitable foruse on forming fabrics has been further impeded because of physicalcharacteristics other than strengths which are required for suchfabrics. For example, forming media, including the seam portions must be(1) capable of passing large amounts of water from the furnish, and yetretaining most of the deposited fibers, (2) flexible, (3) smooth anduniform in order to prevent marking or undue marring of the papersurface, (4) dimensionally stable in order to prevent yarn shoving anddimensional changes, which can vary the permeability of the medium andtherefor its drainage and other characteristics, as well as thecharacteristics of the paper formed thereon from place to place, and (5)resistant to wear and corrosion in the aqueous environment of theforming section.

In accordance with the teachings set forth herein, a fabric seam, andmethod of producing same, is disclosed which has the physicalcharacteristics, as set forth above, required of, for example, a formingfabric, and which is inexpensive and not time-consuming to make.

The resultant porous laminate disclosed herein may also be used in therepair of industrial conveyor belts or papermakers clothing. Forexample, a common occurrence in the papermaking process is for theforming fabric to become ripped or to develop a tear in the body of thefabric. In such cases, if the tear or rip is not repaired, there will bea tendency for the damaged area of the fabric to mark the paper orpaper-like product being produced. Heretofore, attempts have been madeto repair such damaged areas by adhesively bonding a fabric-like patchto the fabric in such a manner that the patch covers the torn area. Withthe advent of synthetic monofilament fabrics, however, there has been atendency for the fabric to fail in the patch area and for the patch tobe torn from the fabric as a result of the stresses to which the fabricand patch are subjected. As explained in greater detail hereinafter,such failure is due at least in part to the low peel strength of thepatch-adhesive-fabric laminates heretofore used. In addition to solvingthe problem of designing a fabric patch which will adhere to, forexample, a monofilament forming fabric for the life of the fabric inquestion, the present invention is directed to a patching process, andproduct produced thereby, by which the physical characteristics of thepatched area of the fabric do not substantially differ from the physicalcharacteristics of the fabric as a whole, as set forth above; that is,the patched area will be (l) fluid permeable. (2) flexible, (3) smoothand uniform, (4) dimensionally stable, and (5) resistant to wear andcorrosion. For example, if the permeability or porosity of a formingfabric at the patched area substantially differs from the permeabilityor porosity of the remaining portion of the fabric, there may be atendency for the paper or paper-like product being produced to becomemarred or marked as a result of the difference. In addition, marring ormarking will-occur if the thickness of the patched area is substantiallygreater than the thickness of the remaining portion of the fabric. Byproducing a patch-scrimfabric laminate in accordance with the teachingsof the present invention, the life of the fabric is prolonged withoutsubstantially reducing the quality of the product being produced. Inaddition, as a result of the ease with which the patch can be applied tothe fabric, as taught herein, papermaking machine shutdown time isminimized. I

In a further application, the porous laminate described herein may alsobe used in the manufacture of duplex or multilayered industrial conveyorbelts or papermakers clothing. For example, it may be employed to form aduplex forming fabric. Such fabrics are useful, for example, in theproduction of high quality paper. In such cases, it is often desirableto utilize a forming fabric comprising a coarse base fabric adhered to afine surface or paper-containing fabric. Heretofore, such fabrics havecomprised two woven layers woven or stitched together. Since themanufacture of such structures requires extensive loom alterations, loomshutdown is necessarily prolonged. The present invention eliminates suchextensive loom shutdown.

It should be noted that the porous laminate disclosed herein is usefulin other applications involving seaming, patching, and multilayeredfabrics; that is, the present invention is not limited to the seamingand patching of forming fabrics, or to the manufacture of duplex ormultilayered forming fabrics. Rather, the teachings of the presentinvention are applicable to other types of industrial conveyor belts,and other types of papermakers clothing, such as press and dryerfabrics, as described and claimed in U.S. Pat. Nos. 3,214,331, Wicker,and 3,192,599, Wagner, respectively, and supplementary papermakersclothing, such as power fabrics, as described and claimed in U.S. Pat.No. 3,222,246, Lee.

The present invention is particularly applicable in those cases wherethe layers which it is desired to bond together are woven from yarnswhich are relatively inert chemically, and, due to their low freesurface energies, difficult to "wet"; that is, substantially encapsulateor cover with adhesive. Because of these physical characteristics, suchyarns are difficult to adhesively bond together. Yarns which have theseproperties include, but are not limited to, polyesters such as Dacron,and polyamides such as Nylon. Such properties are exhibited, forexample, by Dacron yarns, because of the high level of orientation andcrystallinity introduced into the yarn during the manufacture thereof.Although bonding techniques having limited success have been developedin such cases where multifilament yarns are used, this resulting fromthe mechanical interlocking of the constituent fibers of yarns inadjacent layers, since monofilament yarns have smooth, non-poroussurfaces, no opportunity is offered for such mechanical interlocking.Those methods available for modifying such smooth surfaces are complex,lengthy and often include the use of highly reactive and toxicchemicals, such as isocyanates, silanes and chromic acid. Accordingly,any laminate as described herein wherein the constituent yarns comprisemonofilament polyester should be one that minimizes dependence on theinterface for bond strength.

Accordingly, it is an object of this invention to produce a porouslaminated seam for industrial conveyor belts, or papermaking clothing,which will withstand the vigorous treatment said belts or clothing aresubjected to while in operation.

Another object of this invention is to produce a porous laminated seamfor papermaking clothing which is capable of passing large amounts ofwater from the furnish, and yet retaining most of the deposited fibers.

Still another object of this invention is to produce a porous laminatedseam for papermaking clothing which is flexible.

A further object of this invention is to produce a porous laminated seamfor papermaking clothing which is smooth and uniform in order to preventmarking or undue marring of the paper surface.

Still a further object of this invention is to produce a porouslaminated seam for papermaking clothing which is dimensionally stable inorder to prevent yarn shoving and dimensional changes, which can varythe permeability of the medium and therefor its drainage and othercharacteristics, as well as the characteristics of the paper formedthereon from place to place.

Another object of this invention is to produce a porous laminated seamfor papermaking clothing which is resistant to wear and corrosion in theaqueous environment ofthe forming section.

Yet another object of this invention is to produce a porous laminatedseam for papermaking clothing and industrial conveyor belts which isinexpensive and not time-consuming in perfecting.

Still another object of the present invention is to produce a fabricpatch which achieves all of the objects set forth above.

A further object of the present invention is to produce a duplex fabricwhich achieves all the objects set forth above.

SUMMARY OF THE INVENTION This invention achieves these and other objectsby means of a porous laminate comprising a separate first layerinterposed between a second and third layer, said layers bonded togethersuch that the constituent yarns of said layers are continuouslyencapsulated in the bonding means.

DESCRIPTION OF DRAWINGS This invention may be clearly understood byreference to the attached drawings in which:

FIG. 1 is a diagrammatic view of a fabric embodying the teachings of thepresent invention.

'FIG. 2 is a schematic cross-section view along the line 2-2 in FIG. 1.

FIG. 3 is a schematic cross-sectional view of a fabric embodying theprior art.

FIG. 4 is a schematic cross-sectional view of another fabric embodyingthe prior art.

FIG. 5 is a schematic cross-sectional view of another fabric embodyingthe teachings of the present invention.

FIG. 6 is a diagrammatic view of a fabric patch embodying the teachingsof the present invention.

FIG. 7 is a schematic cross-sectional view of a duplex fabric embodyingthe teachings of the present invention.

DESCRIPTION OF PREFERRED EMBODIMENT The embodiment of this invention,which is illustrated in FIGS. 1 and 2, is one which is particularlysuited for achieving the objects of this invention. FIGS. 1 and 2 depicta portion of a single layered fourdrinier forming fabric 2 renderedendless by joining both ends thereof by interposing a separateforaminous scrim material 8 between fabric 2 and an outer fabric layeror seam material 10, and substantially continuously encapsulating theconstituent members of said fabric layers and scrim material with acomposition, such as, for example, a bonding agent or adhesive,substantially continuously throughout at least a portion of the regionwhere they are superimposed with respect to each other. In this manner afluid permeable yet structurally integrated body is produced. Formingfabric 2 comprises warp yarns 4 which extend in the machine directionand filling or weft yarns 6 which extend in the cross-machine direction,said yarns being woven into a four-harness satin weave. While FIG. 2depicts a four-harness satin weave, other types of weaves, for example,twill weaves, may be utilized. Desirably, these yarns are syntheticmonofilaments, such as, for example, polyester and polyamides. It shouldbe noted, however, that any yarn, wire, or strand-like material, hereinreferred to as yarn, having the requisite physical characteristics foruse as a constituent of a forming medium, may be used.

Preferably, outer layer or seam material 10 comprises syntheticmultifilament yarns which have been woven into a plain weave. It shouldbe noted, however, that the present invention is not limited to suchmaterials and constructions, and, as in the case of the fabric 2, anyyarn having the requisite physical characteristics for use as aconstituent of a forming medium may be used. For example, syntheticmonofilaments may be used. In addition, other weave patterns, such as,for example, four-harness satin and leno weaves, may be used. Althoughnot necessary, it has been found that by weaving a seam material 10,which is more permeable than fabric 2, marring or marking of the paperweb at the laminated seam area during the papermaking process issubstantially reduced, if not eliminated. In addition, it has been foundthat marring or marking of the paper web can be further reduced by usinga seam material 10, the constituent yarns of which are smaller indiameter than the constituent yarns of the fabric 2.

Scrim material 8 is separate from and interposed between, therebyserving as an interface for, seam material 10 and fabric 2. Although notnecessary, in the preferred embodiment the scrim material is woven intoa plain weave using yarns which are not chemically inert, and which havehigh surface energies relative to the surface energy of the adhesive orbonding agent, thereby being readily wettable by the adhesive. By way ofexample only, such yarns include glass, cotton and metal. As describedin detail hereinafter, preferably the yarns comprise low twistedmultifilaments or staple fibers. In this manner the adhesive can becaused to penetrate the interstices of the yarns, thereby adding to thestructural integrity or continuity of the composite laminate. However,the scrim material may also comprise monofilament or wire strands.Although not necessary, it is preferred that the diameter of the yarnswhich comprise the scrim material be very small relative to theconstituent yarns of the fabric and seam material. In this manner, thethickness of the seam area is reduced, thereby reducing marring ormarking of the paper web during the manufacture thereof, as noted above.For example, yarns having a diameter of about 40 percent of the diameterof the constituent yarns of the fabric have been found particularlysuitable for use in the scrim material. While scrim material 8, asdepicted in FIG. 1, comprises a plain weave, other types of weaves, forexample, four-harness satin and twill weaves, may be utilized. In anoptimum seam design the porosity of the seam area would be substantiallythe same as the porosity of the remaining portion of the fabric.Accordingly, in order to maximize the porosity in the seam area, it isdesirable, although not necessary, to use a scrim material which has agreater degree of porosity than either the fabric or seam material. Forexample, it has been found that a scrim material which is 50 to 75percent more porous than the fabric, contributes considerably to themaximization of seam area porosity. The composite structure is bonded,as, for example, by using an adhesive 12, such as an epoxy resin. Asexplained hereinafter in greater detail, the bond is perfected such thatthe constituent yarns of the fabric 2, scrim material 8, and seammaterial 10 are encapsulated with the adhesive 12; that is, theconstituent yarns of the forming fabric are encapsulated with theadhesive which in turn encapsulates the constituent yarns of the scrimmaterial and fabric, respectively. In this manner, a fluid permeable yetstructurally integrated body is produced, as depicted in FIG. 2. Forexample, as depicted in FIG. 2, those portions 14 of the scrim material8 which are not in contact or near contact with the seam material 10 orfabric 2 are still encapsulated with adhesive 12 such that the gluelineor adhesive layer 12 is continuous. In this manner, the forces exertedon the glue-line during, for example, the papermaking process, areevenly distributed throughout the seam area due to the structuralintegration of the adhesively bonded seam-scrim-fabric laminate. Asnoted above, desirably the diameter of the constituent yarns of thescrim material 8 is less than the diameter of the yarns which comprisethe fabric 2. The relatively large yarns of the fabric 2 are required sothat the forming fabric will be strong enough to withstand the forcesexerted upon it during the papermaking operation. By using relativelysmaller yarns in the scrim material 8, it is possible to encapsulatethem substantially entirely in the adhesive 12 at those points where thescrim yarns come into contact or near contact with the fabric or seammaterial. The continuity of the glue-line can be further perfected byusing a scrim material comprising multifllament yarns which may beimpregnated with the adhesive 12. For example, untwisted multifilamentyarns have been found to be particularly suitable for use in the presentinvention.

Although the direction in which the constituent yarns of the seammaterial, scrim material, and fabric extend relative to each other isnot critical to the teachings of the present invention, preferably theyarns of the seam material and fabric are parallel relative to eachother, the yarns of the scrim material being disposed 45 thereto.

Without wishing or intending to be bound by a theory of operation, it isbelieved that a porous laminated structure having superior strength, asdisclosed herein, is achieved as a result of the intermediate scrimmaterial being encapsulated with the bonding agent or adhesive, and theresultant composite structure being structurally integrated with boththe seam material and the forming fabric as a result of the simultaneousencapsulation of the scrim material with the constituent yarns of thefabric and seam material. Put another way, the adhesive coating 12 onthe scrim material 8 is continuous with, and, in fact, a part of theadhesive coating 12 on the fabric 2 and seam material 10 at points ofcontact or near contact between the scrim material 8 and fabric 2 andscrim material 8 and seam material 10. In this manner a physical ormechanical bond, as distinguished from an adhesive bond, is perfected;that is, a bond is perfected which is more dependent upon the physicalrelationship between the seam material, scrim material, adhesive, andfabric, than the adhesive characteristics of the constituent materials.As depicted in FIG. 2, those portions of the scrim material which arenot in contact or near contact with the seam material or fabric arestill encapsulated with adhesive 12 such that the glue-line or adhesivelayer is continuous. In this manner, the bonding material substantiallycontinuously encapsulates the constituent members of the fabric layersand scrim interface.

The present invention is to be distinguished from the compositestructure 16, depicted in FIG. 3, wherein adjacent layers 18 and 20 areaffixed to one another as a result of surface adhesion, as distinguishedfrom yarn encapsulation, perfected by means of an adhesive. Such a bonddepends on the adhesive qualities of the bonding agent or adhesive 22and the yarns which comprise the various layers of the laminate, and thedegree of contact area between adhesive 22 and said yarns. The presentinvention is also to be distinguished from the composite structure 24depicted in FIG. 4 wherein the layers 26, 28 are bonded together bymeans of an adhesive 30, which encapsulates the constituent yarns ofadjacent layers. It should be noted that laminate 24 does not includethe intermediate scrim material disclosed in the present invention.

The present invention is not limited to the embodiment depicted in FIG.1, however. For example, as depicted in FIG. 5, a seam may be perfectedwherein the seam material described above is actually part of thefabric. By overlapping both ends 32, 34 of fabric 36 interposingtherebetween scrim material 38, and adhesively bonding the compositelaminate as described herein, a porous seam structure which iscontinuously integrated is perfected wherein one end 32 of the fabric 36takes the place of the seam material. Alternatively, prior to joiningfabric 36, a strip of scrim material 38 may be adhesively bonded toopposite sides of fabric 36 at both ends thereof. Subsequently, portionsof the adhesive may be removed from the surface of the scrim materialwhich is not adhered to fabric 36. Finally, the scrim material attachedto one end of the fabric may be positioned in face-to-face contact withthe scrim material attached to the other end of the fabric and thecomposite fabric-scrim-scrim-fabric laminate adhesively bonded.

In accordance with one embodiment of this invention, illustrated in FIG.6, a portion of a forming fabric 42 which has been patched is depicted.As in the case of the fabric seam discussed above, the patched area 44of fabric 42 comprises a scrim material 46 interposed between an outerlayer or patch material 48 and fabric 42, the composite structure beingbonded as described herein. In this manner, a patched area is perfectedwhich is porous yet structurally integrated with the forming fabric, thebond being substantially as strong as, if not stronger than, theconstituent materials which comprise the fabric 42. In addition, byperfecting the bond in accordance with the method described hereinafter,the physical characteristics of the patched area of the fabric aresubstantially the same as the physical characteristics of the fabric asa whole.

FIG. 7 illustrates a further application of the teachings of the presentinvention, depicting a duplex or multilayered forming fabric. The fabric52 comprises a scrim material 54 interposed between a base layer 56 andpaper contacting or outer layer 58. The composite structure is bonded,as, for example, by using an adhesive such as an epoxy resin. As in thecase of the fabric seam and patch, duplex fabric 52 is a structurallyintegrated whole, having the physical characteristics required offorming fabrics, as set forth above.

The process of joining two layers of fabric to each other at their flatsurfaces comprises the steps of interposing between the layers at leastone separate layer of foraminous material, and substantiallycontinuously encapsulating the constituent members of such fabric andinterposed layer(s) with a material throughout at least a portion of theregion where the layers are superimposed with respect to each other.Although not necessary, in order to maximize the porosity of thecomposite structure, any excess adhesive which may exist in theinterstices of the structure may be removed. In addition, in some casesit may be desirable to cure the encapsulating material. For example,when the laminate is produced by interposing between two layers offabric a separate scrim material, and substantially continuouslyencapsulating the constituent members of such fabric and scrim materialwith an adhesive such as an epoxy resin, it may be desirable to cure theepoxy resin by, for example, subjecting the laminate to heat and/orpressure. The encapsulating material may be added before or after thelayers have been positioned relative to each other.

In order to obtain a greater bonding area, that is, more surface contactbetween one fabric layer and scrim material, and between the otherfabric layer and scrim material, the surfaces of the fabric layers whichwill be adjacent to the scrim material when the laminate has beenperfected, may be rendered planar, as, for example, by sanding same. Thebond may be further strengthened by thoroughly drying the fabric layersin the area to be laminated, thereby reducing any tendency for theadhesive to become degraded by moisture. A more porous laminate may beperfected if, after the encapsulating material or bonding agent isapplied to the inner fabric layer, and before the outer fabric layer andscrim material are subjected to the adhesive and positioned on the innerlayer, any excess adhesive is removed from the interstices of the innerlayer as by blowing air under pressure through the fabric. In addition,after the outer layer and scrim material have been encapsulated with thebonding agent, and positioned on the inner layer, any additional bondingagent which exists in the interstices of the composite structure may besimilarly removed.

When, for example, the encapsulating material or bonding agent is curedby subjecting it to heat, care must be taken that the temperature not begreater than the melting point of the constituent material comprisingthe fabric layers and scrim material. For example, in those cases wherethe fabric and seam material comprise polyester monofilament yarns, anadhesive having a curing temperature less than 300 F. should be used. Anamine cured epoxy resin would be suitable in such applications. In thisconnection, it should be noted that although not necessary, epoxy-basedadhesives are particularly suited for the present invention since theiradhesive properties are not lost in those cases where the particularapplication requires that the base epoxy be modified with such additivesas flexibilizers, filters, diluents, viscosity control agents, cureaccelerators, high temperature stabilizers, and the like. Other examplesof suitable encapsulating materials include, but are not limited to,phenolics, unsaturated polyesters, and rubber based adhesives. Theencapsulating material may be in any form. For example, it may comprisea scrim material which, when subjected to heat, melts and encapsulatesthe various yarns of the resultant laminate.

EXAMPLE 1 Two pieces of fabric were joined by adhesively bonding onepiece to the other, as set forth herein. Each fabric comprised 8 milmonofilament polyester yarns woven into a four-harness satin weavewherein there were 83 picks per inch and 48 ends per inch. One end ofone fabric was brought into contact with one end of the other fabricacross the full width thereof. The abutting ends were joined bypositioning an outer layer or seam material in face-to-face engagementwith both fabrics such that the seam material extended onto each fabricacross the full width thereof about one inch, the yarns of the seammaterial being substantially parallel to the yarns of the joined fabric.The outer layer or seam material comprised three ply multifilamentpolyamide warp yarns and three ply multifilament polyester weft yarnswoven into a four-harness satin weave wherein there were 71 picks perinch and 48 ends per inch. Prior to assembling the laminate, the seammaterial was treated with resin and heat set for stabilization; thesurface of the seam material to be positioned in face-to-face engagementwith the abutting ends of fabric being sanded to increase the surfaceroughness. An epoxy resin with an amine hardener was applied to the seamarea and the composite structure cured at 250 F. for minutes at aboutone pound per square inch pressure. The joined fabric was subjected totensile forces. At about 106 pounds per lineal inch of width, the seamfailed, the failure occurring at the adhesive-fabric'interface orglue-line.

EXAMPLE 2 A second fabric was joined as set forth in Example 1, exceptthat in this case, a scrim material was interposed between the abuttingfabrics and the outer layer or seam material in accordance with theteachings of the present invention such that the yarns which comprisethe scrim material were disposed 45 relative to the yarns which comprisethe fabric and seam material. The scrim material comprised multifilamentglass yarns having zero twist woven into a plain weave wherein therewere ends per inch and 20 picks per inch. The scrim material was aboutthree mils thick. As in Example 1, the joined fabric was subjected totensile forces. At about 210 pounds per lineal inch of width, the seamfailed. Not only was the laminated seam produced in accordance with theteachings of the present invention about 100 percent stronger than theseam described in Example 1, but, in addition, the continuous orstructurally integrated glue-line was stronger than the constituent yamsof the outer layer seam material, since the failure did not occur at theglue-line. Rather, at 2 [0 pounds per lineal inch of width, the yarnswhich comprised the seam material broke.

EXAMPLE 3 A third fabric was joined as set forth in Example 1, exceptthat the fabric comprised three-ply multifilament polyamide warp yarnsand three-ply multifilament polyester weft yarns woven into afour-harness satin weave wherein there were 41 picks per inch and 30ends per inch. In addition, prior to assembling the laminate, the fabricwas treated with resin and heat set for stabilization, the portion ofthe surface of the fabric to be positioned in face-to-face engagementwith the seam material being sanded to increase the surface roughness.This fabric could not be subjected to tensile forces because the seamedarea fell apart when the fabric was picked up, thereby indicating thatthe seam had about zero tensile strength.

EXAMPLE 4 A fourth fabric was joined as set forth in Example 3, exceptthat a scrim material was interposed between the seam material andfabric as described in Example 2. The joined fabric was subjected totensile forces. At about 93 pounds per lineal inch of width the seamfailed, the failure occurring at the adhesivefabric interface orglue-line. Accordingly, the laminated seam produced in accordance withthe teachings of the present invention was about 93 percent strongerthan the seam described in Example 3.

EXAMPLE 5 A torn fabric comprising 8 mil monofilament polyester yarnswoven into a four-harness satin weave having 83 picks per inch and 48ends per inch was re aired by positioning a fabric patch over the tornarea and adhesively bonding the composite structure as set forth inExample 1. The porosity of the fabric was 20.3 gallons per minute perfoot squared (gpm/ft The patch material was woven into a plain weave,using yarns which comprise multi-filament polyester and polyamidefibers, wherein there were 50 picks per inch and 50 ends per inch. Thepatch material was treated with resin and heat set for stabilization,the surface of the patch material to be positioned in face-to-faceengagement with the fabric being sanded to increase the surfaceroughness. The peel strength of the patch was measured at 1.2 pounds.The porosity of the patched area was reduced by about 25 percent to 15gpm/ft EXAMPLE 6 A second patch was applied to the fabric described inExample 5 in the same manner as set forth therein, except that a scrimmaterial was interposed between the fabric and the patch material. Thepeel strength of the patch was measured at 3 pounds. Although the peelstrength of the laminated patch produced in accordance with the presentinvention was more than percent greater than the patch described inExample 5, there was only a 20 percent reduction in porosity.

The embodiments which have been described herein are but some of severalwhich utilize this invention and are set forth here by way ofillustration but not of limitation. It is apparent that many otherembodiments which will be readily apparent to those skilled in the artmay be made without departing materially from the spirit and scope ofthis invention.

I claim:

1. A means for joining two layers of woven fabric to each other at theirflat surfaces comprising at least one foraminous layer interposedbetween and separate from both of said layers of fabric, and acomposition which substantially continuously encapsulates theconstituent members of said fabric layers and said interposed layersubstantially continuously throughout at least a portion of the regionwhere they are superimposed with respect to each other.

2. The article described in claim 1 wherein the free surface energy ofsaid composition is less than the free surface energy of said foraminouslayer.

3. The article described in claim 2 wherein said foraminous layer is aglass scrim.

4. The article described in claim 3 wherein said glass scrim comprisesmultifilament yarns.

5. The article described in claim 4 wherein said glass scrim is woven.

6. The article described in claim 5 wherein said glass scrim is woveninto a plain weave.

7. The article described in claim 6 wherein said glass scrim is wovenfrom multifilament yarns.

8. The article described in claim 2 wherein said composition is an epoxyresin.

9. The article described in claim 8 wherein said foraminous layer is aglass scrim.

10. The article described in claim 2 wherein at least one of said twolayers is woven from synthetic yarns.

11. The article described in claim 10 wherein said yarns are syntheticpolyesters.

12. A porous laminate comprising a first layer interposed between asecond and third layer, said first layer being woven into a plain weavefrom multifilament glass yarns,

said second and third layers being woven from synthetic polyester yarns,

said yarns of said second and third layers being disposed substantiallyparallel to each other and at about 45 to said yarns of said firstlayer,

said layers being adhesively bonded together with an epoxy resin suchthat said resin substantially encapsulates the constituent members ofall of said layers substantially continuously throughout at least aportion of the region where they are superimposed with respect to eachother.

13. A method of joining two layers of fabric to each other at their flatsurfaces comprising the steps of interposing between said layers atleast one separate layer of foraminous material, and substantiallycontinuously encapsulating the constituent members of said fabric andsaid interposed layers with a composition throughout at least a portionof the region where said layers are superimposed with respect to eachother, by applying a bonding agent to all of said layers, removing anyexcess bonding agent from the interstices of said layers, and curingsaid bonding agent.

14. A method according to claim 13 in which said curing involvessubjecting said bonding agent to heat and pressure.

2. The article described in claim 1 wherein the free surface energy ofsaid composition is less than the free surface energy of said foraminouslayer.
 3. The article described in claim 2 wherein said foraminous layeris a glass scrim.
 4. The article described in claim 3 wherein said glassscrim comprises multifilament yarns.
 5. The article described in claim 4wherein said glass scrim is woven.
 6. The article described in claim 5wherein said glass scrim is woVen into a plain weave.
 7. The articledescribed in claim 6 wherein said glass scrim is woven frommultifilament yarns.
 8. The article described in claim 2 wherein saidcomposition is an epoxy resin.
 9. The article described in claim 8wherein said foraminous layer is a glass scrim.
 10. The articledescribed in claim 2 wherein at least one of said two layers is wovenfrom synthetic yarns.
 11. The article described in claim 10 wherein saidyarns are synthetic polyesters.
 12. A porous laminate comprising a firstlayer interposed between a second and third layer, said first layerbeing woven into a plain weave from multifilament glass yarns, saidsecond and third layers being woven from synthetic polyester yarns, saidyarns of said second and third layers being disposed substantiallyparallel to each other and at about 45* to said yarns of said firstlayer, said layers being adhesively bonded together with an epoxy resinsuch that said resin substantially encapsulates the constituent membersof all of said layers substantially continuously throughout at least aportion of the region where they are superimposed with respect to eachother.
 13. A method of joining two layers of fabric to each other attheir flat surfaces comprising the steps of interposing between saidlayers at least one separate layer of foraminous material, andsubstantially continuously encapsulating the constituent members of saidfabric and said interposed layers with a composition throughout at leasta portion of the region where said layers are superimposed with respectto each other, by applying a bonding agent to all of said layers,removing any excess bonding agent from the interstices of said layers,and curing said bonding agent.
 14. A method according to claim 13 inwhich said curing involves subjecting said bonding agent to heat andpressure.